The base flange of a wellhead is the element that makes it possible to provide the junction and ensure sealing between a tubing that comes from the bottom of the well and a surface facility from which connecting pipes convey what is produced by the well, for example oil, gas or water, to a distribution grid.
The base flange, which is installed during construction of the well, may undergo deteriorations over time, in particular due to corrosion, resulting from leaks. When the base flange must be restored, it is necessary to stop the well, purge it, and disassemble the wellhead to be able to restore the base flange and adjacent elements, in particular the tube on which the wellhead is mounted, or, if applicable, install new pieces.
Stopping a well being expensive, it is only possible in exceptional cases. Thus, the repair of a base flange of a wellhead is considered impossible.